CCTM emission module


Hi CMAQ users and developers:
I was running CCTM with my own input, and it seems that when CTM_PT3DEMIS is set to “N”, the CCTM output is not sensitive to surface emission.
In order to confirm this, I run the benchmark case, with CTM_PT3DEMIS set to “N”. Then, I manually create the surface emission files for benchmark run, with the same gridding, same species, same time flag as benchmark input, but set the emission rate for each grid to zero. So basically, benchmark case, but with no surface emission. The CCTM output shows, the concentrations for all species of benchmark case and benchmark case with no surface emission are exactly equal. In another words, the CCTM does not take the surface emission files into account.
I also tried the benchmark case with CTM_PT3DEMIS set to “Y”, the simulation result shows the concentrations in CCTM output is sensitive to both surface and in-line emissions
All the runs were successful, without error message. My questions are:

  1. Is there anything particular on the scripts or files that I need to be careful about, in order to prevent from this kind of result?
  2. Or, did I just compile the CMAQ improperly, so that the emission module neglects the surface emission file, when CTM_PT3DEMIS is set to “N”?

It will be awesome if anyone could take some time to look into this issue. I could email you all the necessary log files, CCTM output files, modified input files, etc, if it helps on solving this case.



Hi Huan,

Thanks for reaching out to the Forum. It’s not clear immediately why setting CTM_PT3DEMIS to N would disable the surface emissions. If you do share your logs and run script with us, we may be able to determine something more significant. Also, what version of CMAQ are you running?

It’s important to note that CMAQv5.3 (now available in Beta) introduces comprehensive revisions to these features. For that version, you can independently set the number of gridded and inline emission files, or set either or both of them to 0 to turn them off. We have also added extensive diagnostic output to better document the options that were invoked for any simulation.

Ben Murphy


Hi Ben:
That is exactly what I need to know about. As I stated in the previous post, I sent CTM_PT3DEMIS to N, then run with the surface emission file, and a “fake” surface emission file with 0 emission rate, the concentration of every species from these two runs are the same.
I am using CMAQ v5.2.1
I am not able to upload the files here, below are the links to the github:



Hi Huan,

Sorry for the delay in responding to your issue. I think the problem is an inconsistency between the number of vertical layers on your gridded emission files and the number of layers expected by the CMAQ emissions read statements (NLAY=35). There could be an error in the logic in the file EMIS_DEFN.F somewhere between lines 172-193 or between lines 280-302. Could you tell me how many layers are on your input emission files?

Again, please note that CMAQv5.3 resolves all of these issues and adds more documentation for better transparency.